Air China Flight 106, a Boeing 737-800 traveling from Hong Kong to Dalian, dropped from 35,000 feet to 10,000 feet within 10 minutes earlier this week. The question is, why?
Ostensibly the answer is because the flight lost pressure in the cabin. But why did the cabin lose pressure? That’s where the issue becomes more complicated. The incident occurred about 30 minutes after takeoff. After deploying oxygen masks and dropping to 10,000 feet, the aircraft began climbing again and continued to its final destination.
This leaves me with two questions:
- How did this de-pressurization occur on a relatively new 737-800?
- Why did the pilots not divert, out of an abundance of caution?
The two questions may be linked by one word: smoking. At least that’s the word from People’s Daily, a state-run newspaper in China that cites unnamed sources to report that the pilots had been smoking in the cockpit.
Remember that flight deck side windows open. Did one of the pilots attempt to extinguish cigarette through a window? Or could excessive smoke or a fire in the cockpit have prompted the window opening? Opening a window, even a crack, could certainly have led to the depressurization. A cockpit window is not like an aircraft door, where intense pressure at high altitudes makes it virtually impossible to open thanks to the locking mechanism on it.
I’m surprised the pilots did not divert. After 12-15 minutes, all the oxygen was gone from the passenger air masks. Did pilots forgo a diversion into order to hide evidence of smoking?
A Second Scare
Toward the end of the flight, FAs made an announcement to put the oxygen masks back on. Small problem: they were empty. It turned out to to be a false alarm, but had it been a real emergency there was no oxygen inside.
Air China is taking the matter very seriously. It has stated:
If the investigation reveals that the crew has violated regulations, the company will seriously deal with the responsible person with zero tolerance.
Apparently, Air China regulations prohibit crew members from smoking onboard, even in the cockpit or crew rest areas.
UPDATE: It Was Smoking!
Chinese authorities have now confirmed smoking is to blame for the incident:
A senior official from the Civil Aviation Administration of China (CAAC) told reporters Friday that, without notifying the pilot, the unnamed co-pilot was trying to turn off air recycling fans to prevent the vapor from spreading into the passenger cabin.Instead, he toggled the wrong switches, which were close to his intended target, leading to a drop in oxygen levels which triggered altitude warnings.Qiao Yibin, the CAAC official, promised to hand down “severe punishment in accordance with laws and regulations,” if the regulator’s final conclusion on the incident matches its initial finding.
As One Mile at a Time did, it’s fair to mention that it’s not like the aircraft was ever free-falling. But a 25K foot drop in 10 minutes is off-putting, to say the least. Having been on a China Eastern flight that smelled like an ashtray, I hope that if the pilots were smoking, they will be dealt with harshly. More broadly, the Civil Aviation Administration of China should take additional steps to dissuade pilots from lighting up onboard.
My biggest concern is that the captain put all 153 passengers at risk by failing to divert because of the depleted oxygen. Had another emergency occurred that required oxygen, passengers would have been up the creek without a paddle. That’s a sobering thought far more important than the smoking issue.
Am I fair to question the pilots here, regardless of the cause of the depressurization? Would you fly Air China after this incident?